1. Field of the Invention
The present invention relates to a method of detecting a foreign matter caught by a window (hereinafter, referred to as a foreign matter detecting method) in a power window device, and more specifically, to a foreign matter detecting method of a power window device capable of correctly and effectively detecting that any foreign matter is caught by a window while it is being opened or closed in the state that a memory has a reduced storing capacity.
2. Description of the Related Art
There have been known various types of power window devices for an automobile which detect a foreign matter caught by a window and one of the devices is a power window device disclosed in Japanese Unexamined Patent Publication No. 61-60981.
The power window device disclosed in Japanese Unexamined Patent Publication No. 61-60981 uses a motor load current value as a parameter value for detecting a foreign matter caught by a window. In the device, the entire moving region of the window is equally divided into a plurality of divided moving regions and a reference current value is preset to each of the divided moving regions to indicate whether the foreign matter is caught by the window or not. While the window is moving, the motor load current value is detected and the detected motor load current value is compared with a reference current value. When the detected motor load current value greatly exceeds the reference current value, it is determined that the foreign matter is caught by the window and the movement of the window is stopped.
In this case, the reference current value in the power window device disclosed in Japanese Unexamined Patent Publication No. 61-60981 is set to each of the divided moving regions based on a peak motor load current value which is obtained when no foreign matter is caught while the window is moving in the divided moving region. Even if the reference current value is set once, it is not always fixedly used but properly renewed depending upon a peak motor load current value which is obtained when the window moves in the respective divided moving regions. That is, the reference current value has a learning function.
As described above, the power window device disclosed in Japanese Unexamined Patent Publication No. 61-60981 is arranged such that the entire moving region of the window is equally divided into the plurality of divided moving regions and the reference current value is preset to each of the divided moving regions to determine whether a foreign matter is caught by the window or not. Accordingly, the power window device has an advantage that it can more accurately detect whether a foreign matter is caught by the window or not.
The applicant has also proposed a power window device, in addition to the above power window device, for detecting a foreign matter caught by a window, the device being arranged such that motor load torque is used as a parameter value for detecting the foreign matter caught by the window, the entire moving region of the window is equally divided into a plurality of divided moving regions and a reference median is preset to each of the divided moving regions to detect whether the foreign matter is caught by the window or not.
Incidentally, any of the power window device disclosed in Japanese Unexamined Patent Publication No. 61-60981 and the power window device having been proposed by the applicant presets the reference current value or the reference median to each of the plurality of divided moving regions which are obtained by fixedly and equally dividing the entire moving region of the window. Thus, there is no difference between the reference current values or reference medians preset to adjacent divided moving regions. Otherwise, the difference between them is very small in many cases. At the time, a memory provided with a control unit of the power window devices includes a storing area for storing the reference current value or reference median preset to each of the divided moving regions. The reference current values or reference medians are stored in the storing area of the memory even if they are not almost different between the adjacent divided moving regions.
Since a lot of the reference current values or reference medians are stored in the storing area of the memory in any of the aforesaid power window devices, there is a problem that the capacity of the storing area must be increased and it is difficult to effectively use the storing area of the memory.
To solve the above problem, an object of the present invention is to provide a foreign matter detecting method in a power window device, the method being capable of effectively using the storing area of a memory and reducing the storing capacity of the memory while increasing the certainty for detecting the foreign matter caught by the window.